In general there are two types of the vehicle wheel bearing apparatus. Those for a driving wheel and those for a driven wheel. In either type of wheel bearing apparatus, there is a desire to reduce manufacturing costs, weight and size in order to improve fuel consumption. A well known representative of a prior art wheel bearing apparatus for a driven wheel is shown in FIG. 4.
The wheel bearing apparatus of FIG. 4 is a so called “third generation type”. It includes an inner member with wheel hub 51, an inner ring 52, an outer member 53, and double row balls 55, 55 contained between the inner member 51, 52 and the outer member 53, via cages 54. The wheel hub 51 is integrally formed at one end with a wheel mounting flange 56. The flange 56 mounts a wheel (not shown). The outer circumference on the wheel hub includes an inner raceway surface 51a and has a cylindrical portion 51b that axially extends from the inner raceway surface 51a. In addition, the hub bolts 58 secure both a wheel and a brake rotor 57. The bolts 58 are arranged equidistantly along the periphery of the wheel mounting flange 56.
The inner ring 52 is formed with another inner raceway surface 52a on its outer circumference. The inner ring 52 is press-fit onto the cylindrical portion 51b of the wheel hub 51. The inner ring 52 is prevented from axially slipping off of the wheel hub 51 by a securing nut 59. The nut 59 is adapted to be fastened to a male thread formed on the end of the cylindrical portion 51b. 
Double row outer raceway surfaces 53a, 53a are formed on the inner circumference of the outer member 53. The double row balls 55, 55 are freely rollably contained between the double row outer raceway surfaces 53a, 53a and the oppositely arranged double row inner raceway surfaces 51a, 52a. 
A knuckle 60, forming part of a suspension apparatus, is fit onto the outer circumference of the outer member 53, via a serration. A caulked portion firmly secures the knuckle onto the outer member 53. Similarly, the brake rotor 57 is firmly secured to the wheel hub 51 by caulking the end of the wheel hub 51. Such a fixation, via caulking, reduces the number of parts and thus the weight of the bearing apparatus while simplifying its assembling process (e.g. see Japanese Laid-open Patent Publication No. 328401/2001).